Electronic pipettes are traditionally adjusted and controlled by pressing keys. For example volume adjustment is often implemented in this way. A standard implementation is arrow keys with which the volume can be adjusted to be increased or decreased. Almost without exception, the same arrow keys are also used for other functions, for example for advancing in a menu. Conventionally a single touch of an arrow key causes a change of one adjustment step, and pressing the key for a longer period will result in an accelerated change of the reading. However, an adjustment carried out in this way has its drawbacks. The adjustment is not very fast at least in case the adjustment target value is far from the initial reading. Moreover the keys are often in connection with the display and can thus be ergonomically poorly located. There are designs where functions are adjusted using adjustment wheels, but they have not as yet brought any improvement to the speed or ease of the adjustment.
In document WO 2010/034290 A2, an electronic pipette is described, which comprises an adjustment wheel that also functions as push key. With the adjustment wheel one can select the volume, control calibration and proceed in the menu.
In document EP 1 878 500 A1, a pipette is described that has an adjustment wheel that allows, by rotating it, the selection of mode of use, for example manual pipetting, pipetting and mixing, titration and so on. This function is not connected to a push key but resides in a separate adjustment wheel.
EP 1 632 840 A1 describes a pipette having a display on its hook in front of which there is an adjustment wheel. With the adjustment wheel functions can be selected, such as the volume of the liquid to be pipetted, proceeding in the menu, calibration of the pipette, etc.
The solutions mentioned above are such in which the adjustment wheel is of the incrementally rotating type. There are also solutions having a touch screen with a touch wheel. In existing, such as those mentioned above, adjustment wheel solutions of this type the adjustment wheel is of the same type as the adjustment wheel of a car radio. This solution does not offer good control sensitivity especially when the reading needs to be changed much at once and to an accurate specific value. To speed up the adjustment in this case the wheel needs to be rotated fast in pulses for a fast change of the reading. This will easily lead to exceeding or falling short of the wanted reading, and setting the accurate reading will cause additional iteration.